A. FIELD OF THE INVENTION
The present invention relates to bending and punching machines, and more particularly to a channel forming and punching machine which simultaneously bends a metal plate as a "U" shaped channel and punch both side walls and the web thereof in a single machine and a single operation
B. DESCRIPTION OF THE RELATED ART
There is a number of well known bending machines for bending metal pieces such as wires, plates, etc., of the type wherein a metal piece is firstly bent by pressing such piece by means of a pressing member against a support member having a predetermined pattern.
With this type of machines a great variety of metal pieces can be manufactured, including channel shaped pieces of the type wherein a large metal plate is bent by its longitudinal edges usually at about 90.degree., which are used for multiple purposes such as in the automotive industry for the manufacturing of truck chassis or automotive chassis.
Usually, in the forming of a metal component, several stages are needed in the forming process. Each stage involves tools or specialized machines for performing some tasks (for example laminating, bending, piercing, etc.), therefore, when the forming process is long, the stages and the number of tools or machines is high and the production process of the final product usually takes a lot of time.
An efficient production process must have a minimum of stages in order to reduce the number of machines and consequently reduce the investment in equipment. With a less number of stages and machines, the production speed may be increased, a better client service is achieved since the product is delivered more quickly and savings in energy and manpower costs are obtained.
Also with less stages in the production process, the logistic system of the plant is optimized since the distribution of the equipment and production lines in the plant is compacted and therefore less inventory in process is obtained and a better flow of the product trough the production system is achieved.
The most common stages in the forming of metal pieces are the piercing and bending steps, which actually are carried out in separate machines. Therefore it is highly desirable to carry out the steps of piercing and bending in a single operation and in one machine in order to simplify the step of only piercing and only bending.
For some specific uses, the side walls of the channel need to be punched. The punching step was very difficult to carry out when the channel was already formed and usually at least one punching machine was necessary for punching firstly one side wall, and then the other. One alternative to avoid the above step is to punch a flat large metal sheet before the channel is formed, but there is the need of calculating the exact location of the perforations in the metal sheet in order to guarantee that the perforations reach the correct position when the channel is formed, which is very difficult to achieve and it is not reliable.
One bending machine for forming "U" pieces such as rounded bars, channels, sections and the like, is disclosed in U.S. Pat. Nos. 4,798,073 and 4,890,469 both of Dischler, which comprises two opposed spaced bending devices, each including at least two bending components and drive means to move at least one of the bending components essentially transversely to the length of the piece to be bend.
To produce a rounded "U" shaped piece, the piece to be bent is placed between the bending components of each of the bending devices and then, a bending moment is applied by the bending components of two of the bending devices, acting transversely to the longitudinal axis of the piece. Due to the application of such bending torque the piece is bent in a rounded "U" shape.
Such machine, cannot produce pieces with side walls at about 90.degree. and it is not possible to punch the sides of the rounded "U" shaped piece or a channel in the same machine.
In the actually known art, although highly desirable, there is no machine available which be capable of simultaneously bend a metal plate as a "U" shaped channel, and punch one or both side walls thereof in a single machine and in a single operation, mainly because there was no possibility to punch the side walls and/or the web of the channel when it is being formed in the same stroke.
Considering the above referred problems, applicants developed a channel forming and punching machine, which simultaneously forms a channel from a metal sheet and punches the side walls of a formed channel, comprising: a lower member including: a support frame; a die member mounted on the support frame, said die member having a sheet receiving surface and two side walls each having perforations at a desired height; and an upper member, mounted on a lowering and lifting mechanism, actuating on the lower member, and including: a support frame; a female member retained by the support frame, said female member having an upper wall and two depending side walls each having perforations at a height coinciding with the perforations of the die member, said upper wall and said side walls forming a channel shaped housing which receives the die member when the upper member is lowered to form a channel; a blank holder, resiliently retained into the channel shaped housing of the female member, for retaining a metal sheet to be bent; and punching elements coupled at the ends of the female member, for punching the side walls of a formed channel, passing through the perforations of the female member and the die member.
Since the forming and punching process are carried out in one machine, there is no need to invest in separate punching and bending machines (which generally are large), besides saving plant space and energy costs.